Despite Diane’s comment, Nathan avoided stepping on the FBI seal as he followed. It didn’t feel right walking on it. Frank maneuvered himself behind his desk while Nathan, Harvey, and Greg sat in tan leather chairs arranged in a semicircle. Nathan studied the photos behind Frank’s desk. They displayed him shaking hands with five different presidents: Carter, Reagan, Bush, Clinton, and George W. Bush. Frank stood in the Carter, Reagan, and first Bush photographs and was in a wheelchair for the other two. Portrait-type pictures of his two adult children were hung on the wall to his right: Greg and presumably a daughter. Nathan waited through an uneasy silence while Frank reached into a side drawer and pulled out a thick file. Nathan looked at it, then back to Frank.

“I know your father well. We go back a long way.”

Nathan said nothing.

“He’s a good man,” Frank said quietly.

Nathan locked eyes. “We aren’t here to talk about him.”

Out of Frank’s line of sight, Nathan felt Harv nudge his foot. If Greg had noticed the gesture, he didn’t react.

“No, that’s true. We’re here to talk about my grandson. He’s MIA. Has been for several days now. He was undercover inside an arms-smuggling operation up in Lassen County. An outfit called Freedom’s Echo.” Frank paused for a moment. “How much do you know about Semtex?”

“It’s Czech-made plastic explosive.”

“That’s right. Extremely potent stuff. And we know for a fact that this group got their hands on some of it, a lot of it, actually. Around a ton. It was the last thing my grandson reported before he disappeared. It’s likely he blew his cover relaying the information.”

“That’s a bad situation,” Nathan said.

“And not just for him. Seizing the Semtex is critical. In the wrong hands, it could mean several more World Trade Center-type incidents. A few well-placed car bombs in the underground parking structures of skyscrapers could bring them down. Unlike the World Trade Center, there wouldn’t be time for an evacuation. The buildings would collapse with everyone inside.”

Nathan had seen footage of buildings being demolished with explosives. Implosion, he believed they called it. But if you changed the pattern and timing of the charges, the buildings could fall more like trees, taking out other buildings like dominoes. If the Trade Center towers had fallen sideways, it would’ve been worse.

“What exactly do you want us to do?”